Dental chair and the like



A ril 7, 1942 A, J, M Y 2,278,890

DENTAL CHAIR AND I'HE LIKE Filed Feb. 10, 1939 '7 Sheets-Sheet 1 INVENTOR. J

"ZzIsATTORNEYS April 7, 1942. A.'J. MAY

DENTAL-CHAIR AND THEYLIKE 7 She ets-Sheet 2 Filed Feb. 10, 1939 New,

INVENTOR. 5

Jim BY W 94% %z'6ATToRNEYa April 7, 1942. AKJ. MAY 2,278,890

DENTAL CHAIR AND THE LIKE Filed Feb. 10, 1939 7 Sheets-Sheet :5'

1N VENTOR.

a6 v %z'sAFTORNEY$ A. J. MAY

DENTAL CHAIR AND THE LIKE April 7, 1942.

Filed Feb. 10, 1939 '7 Sheets-Sheet 4 N VENT OR, Mizzg 9 ls TToRNEYB April 7, 1942. A. J. MAY 9 DENTAL CHAIR AND THELIKE Filed Feb. 10, 1959 '7 Sheets-Sheet 5 INVENTOR.

A. J. MAY- DENTAL CHAIR AND THE LIKE pril 7, 1942.

Filed Feb. 10, 1939 7 Sheets-She t 6 ltwu ll lll l-ullll I ENTOR ATTORNEYS April 7, 1942. MAY 2,278,890

DENTAL CHAIR AND THE LIKE Filed Feb. 10, 1939 '7 ShetsT-Sheet 7 INVENTOR;

WAZWM %z$ ATTORNEYS Patented Apr. 7, 1942 DENTAL CHAIR AND THE LIKE Adam J. May, Rochester, N. Y., assignor to Bitter Company, Inc., a corporation of Delaware Application February 10, 1939, Serial No. 255,717

5 Claims. (01.

' similar to Fig. '7 showing a modified form of my My invention relates to chairs of the type having a back rest movable relatively to the seat for supporting the back of the occupant in either an upright position or in a reclining position at any desired angle of inclination to the horizontal, and while I have shown and will describe my invention as applied to a dental chair, I desire it to be understood that the invention may be applied also to other surgical chairs, barber chairs, and any other type of chair in which it may have utility.

An object of my invention is to provide such a chair of simple construction wherein the back rest or support may be quickly, easily, and conveniently moved from one position to another with respect to the seat portion of the chair. Another object is the provision of an efficient and reliable means for locking the back portion in any desired position of adjustment and against inadvertent movement in either direction.

Other objects and advantages of my invention will be apparent from the following description when taken in connection with the accompanying drawings, in which:

Fig. l is a side elevation of a dental chair in which my invention is embodied with some parts broken away and others in dotted lines to better illustrate the invention;

Fig. 2 is a view similar to that of Fig. 1 with the back rest or support in an inclined position;

Fig. 3 is a View taken on the line 33 of Fig. 2 in the direction indicated by the arrows;

Fig. 4 is a view taken on the line 4-4 of Fig. 3 in the direction indicated by the arrows;

'Fig. 5 is a plan view of the chair of Fig. 1 with parts removed to better illustrate the invention;

Fig. 6 is a view taken on the line 6-6 of Fig. 5 in the direction indicated by the arrows;

Fig. 7 is a rear view of the chair with parts removed to better illustrate the invention;

Fig. 8 is a view taken on the line 8-8 of Fig. 1 in the direction indicated by the arrows;

Fig. 9 is a view of a part of the back of the chair showing the locking mechanism for the back rest;

Fig. 10 is a view taken on the line III-J of Fig. 9 in the direction indicated by the arrows;

Fig. 11 is a View similar to that of Fig. 9 on an enlarged scale, with additional parts in section, showing the locking mechanism in released position;

and associated parts;

Fig. 13is a view from the right of Fig. 12; Fig. 14 is a fragmentary rear view somewhat Fig. 12 is a top plan view of the locking clamp invention;

Fig. 15 is a view taken on the line l5--l5 of Fig. 16 in the direction indicated by the arrows;

Fig. 16 is a view taken on the line 16-16 of Fig. 15 in the direction indicated by the arrows;

Fig. 17 is a view taken on the line 11-41 of Fig. 15 in the direction indicated by the arrows;

and

Fig. 18 is a side elevation of a portion of Fig. 14.

The same reference numerals throughout the several views indicate the same parts.

The dental chair of my invention comprises a base 2!, a seat part 22, a foot rest 23 and a back rest or support, generally indicated by the numeral 24. The base of the chair comprises a. vertically extending housing or column 25 adapted to enclose a motor and suitable mechanism adapted to raise and lower the level of the whole chair and the patient seated therein. Such elevating mechanism constitutes no part of my present invention and need not be particularly described.

The seat part of the chair comprises, as shown more clearly in Figs. 1 and 5, a seat frame 26 which has a central opening 21, of suitable shape,

at its center and a raised marginal edge 28 for the reception of a cushion 29 of leather or other suitable material. The seat frame 26 and the base column 25 are provided with cooperating parts as indicated at 3| for enabling the tilting of the seat frame with respect to the base column. The foot rest is secured beneath the seat frame by means of bolts 38. Detachably secured to the seat frame, as shown at 32 (Fig. 1), are a pair of arms which may be of any suitable shape and construction. Extending upward from the seat frame at each side thereof is a raised lug or support 33. Each of the supports 33 is provided with a trunnion 34 for the pivotal reception of an arm 36, constituting part of the back rest or support 24. rear of the seat frame 26 is a lug or bracket 31, which is apertured to receive a pin 38 for pivotally connecting a back bar or post 39 to the seat frame.

Formed integral with the arms 36 is a back support 4|, which is provided atits rearward side with slidegro'oves or ways 42 (Figs. 5 and 10). The ways 42 are adapted to receive-cooperating slide parts 43 form'edon a slide 44, which supports a back cushion frame and cushion 46. Suitable means are provided for adjusting the position of the slide 44 in the ways 42 and Extending from the retaining the slide 44 in a desired position. The slide may be adjustably locked in position by suitable mechanism, not part of my present invention, actuated by the hand lever 45. A support 41 for the cushion frame is pivoted to the slide 44, as indicated at 48. The support 4! is pivoted to the frame of the back cushion, as shown at 49. A stop 5! and a spring 52 are provided on the support 51 for enabling a slight movement of the back cushion 46 about the pivot 49 so that the back cushion will automatically adjust itself to the comfort of the patient.

Pivoted to the back support, as shown at 53, is a casting or member E i, which has an elongated opening 55 extending therethrough, adapted to receive the free end of the back bar 39. Mounted in a cutaway portion or enlarged opening 57 in the member 54, and communicating with the opening 56, is a lock or clamp mechanism generally indicated by the numeral 53. The

sired pivotal relation with the seat against movement of the back rest either forwardly or rearwardly. Upon release of the lock mechanism the back rest may be pivoted on the trunnions 34 and with respect to the seat, under the control of a counterbalance mechanism hereafter described. During the pivotal movement of the back rest the back bar 39 slides in the opening 56.

The lock mechanism, as shown more clearly in Figs. 11, 12 and 13, comprises a gripping part or clamp 59, which encircles the back bar 39 and is provided with a slot ti which separates the clamp into two sections which by means later described are drawn together to provide the clamp action. At the rear, as shown in Fig. 12, the clamp is extended to form two lugs 62 and 63, which are separated by the slot Bl. Mounted in the lower part of the lug '63 is a hardened steel pin 64, shown in dotted lines in Fig. 11. Mounted in the lug 62 is a pivot pin 68 adapted to pivotally receive a locking lever 81 the lug being slotted at Til to receive the locking lever. The righthand end -or the locking lever, as viewed in the drawings, has its lower portion split, as shown at 68. The locking lever is threaded at the split portion 68 and provided with a screw 639, the end of which engages the hardened steel pin 64 as shown in Fig 9. A set screw 1! extends through the lower ends of the split portions of the locking lever, and when the set screw 'ii is tightened, the screw 69 is held in any desired adjusted position.

The other or left end of the locking lever 61 extends angularly with respect to the remainder of the locking lever, as shown at T2, and is provided with an aperture 13, which is tapered upward and outward. Extending upward through the aperture 53 in the locking lever is a bar or rod 14, the lower end of which is threaded to receive jam nuts it. The rod i l, above the looking lever 61, is threaded, as shown at H, the threaded portion extending through the member 54. The threads of the rod 14 have a rather long lead so that a relatively slight rotational movement of the rod causes a relatively large movement of the locking lever 61. A washer '18 of suitable material may be interposed between the lower end of the threaded portion of the rod and the locking lever 61.

The rod 14 extends upward at an angle to the back bar (Fig. 11) and projects through the member 54 and has at-its upper end a manually" operable control lever or handle 19. The hand lever may be secured to the rod in any suitable manner, as by a screw 8| which extends into the end of the rod. The hand lever is provided with a lug or projecting finger 82 adapted to limit the movement of the hand lever 19 by the engagement of the lug 82 with the back support 4!, as shown at 83 (Fig. 9). Mounted on the rod 14, by means of a set screw 84, is a collar 85. A tubular housing 8! is secured to the collar and encloses the projecting portion of the rod 14. Encircling the rod and inside the tubular housing 8'! is a torsional spring 88, one end of which, as shown at 89, is secured in the collar and the other end of which, as shown at 9!, is anchored in the member 54.

The action of the torsional spring is to rotate the collar 8%, and therefore the rod M from the position of the parts shown in Fig. 11 to that shown in Fig.9. The rotation of the rod M threads the rod out of the member 54 or in an upward direction so that the rod is moved upward to thereby engage the jam nuts 16 against the lower part of the locking lever 57 and thereby raise the lefthand end of the locking lever. This produces a relative tilting or angular motion between lever 51 and clamp member 5}], about the connecting pin 65, as clamp 59 remains in alinement with the bar 39 on which it slides. Preferably, for positive action, the right hand end 92 of lever fi'l has a loose fit in a recess '93 in member 54, to insure such tilting actuation of the lever by rod 18, while clamp 59 may slide slightly on red Screw 69 of the lever is thus pressed against pin 64 of lug 63 of the clamp which is thus pressed toward lug 62 to clamp the rod 39 therebetween. The parts, as the jam nuts it and screw 69, are preferably so adjusted as to bring about a sufficient gripping of the rod by the clamp just prior to or upon engagement of the lug 82 with the back support 2 5.

Upon manual rotation of lever 59 from the position shown in Fig. 9 to that shown in Fig. 11, the rod 74 is moved in the opposite direction, or downwardly, to thereby move the left hand end of the locking lever downwardly, reversing the above movement of the locking members and allowing the clamp to open and release rod 39. As soon as the control lever i9 is released, spring 83 returns the locking parts to the position first described with the clamp tightly gripping the rod to lock the back of the chair in adjusted position, against movement in either direction.

The counterbalancing mechanism for the chair back will now be described. Secured in a cored out part It: or one of the arms 36, and pivoted to the arm, as shown at W2, is a link I 03, the lower end of is secured'to a lever I04. The outer end of'tlie lever #04 is provided with an opening Hi8 (Fig. '4'), which merges into an angular slot Ill? at the periphery of the end of the lever. The link has a rounded end I08 which fits into the opening 1% and slot It! on the end of the lever I04. The end of the link has an opening for thereception of the stem I09 of a screw PM. A second screw M2 on the other face of the lever HM has a threaded portion H3 which fits in a threaded bore formed in the stem of the screw Hi. There is thus formed a pivot between the link I 83 and the lever I94.

The lever Hi l is pivoted to theinside of seat frame as shown at HB, extends through the opening 21' in the seat frame and at its other end. is provided with an opening for the receptionof' a pin II'I (Fig. 8). A U-shaped fitting H8 is mounted on the pin, straddles the end of the lever I34, and has its lower end'threaded as shown at H3 for the reception of a rod I 20. The rod I is provided at its lower end with a threaded portion I'2I for the reception of a nut I22 provided with a washer, serving as an adjustable stop for a spring I23. The upper end of the spring engages and is seated in a cap I24. Threaded into the cap I24 is a housing I2! which encircles the spring and the rod I23. The lower end of the housing I2! is open so that the end of the rod may move into and out of the opening as shown by a comparison of Figs. 1 and 2. The housing I2'I is provided with two mating openings I28 whichenables a screw driver to be inserted through the openings for the purpose of fastening a bracket I29 to a part of the leg rest 23. The bracket I29 may be welded or otherwise secured to the housing I21.

It willnow be apparent, with the parts in the position shown in Fig. 1, that when the dentist desires to adjust the patient to a reclining position, he releases the hand lever I9 and moves the back rest or support 24 from the position shown in Fig. 1 to that shown in Fig. 2, or to any intermediate position of inclination. During this movement of the back rest, through the link I33 and the lever E04, the spring I23 is being compressed, as shown by the movement of the rod I20 from the position shown in Fig. l to that shown in Fig. 2. As soon as the patient is in the desired reclining position, the dentist releases the hand lever I9 and the back rest or support is automatically locked in the desired position with the spring I23 in a compressed condition. When the dentist desires to erect the patient, he releases the clamp on the back bar 39 by moving the hand lever I9 and raises the back rest from the position shown in Fig. 2 to that shown in Fig. l carrying with it the patient from the reclining position to an upright position.

v A counterbalancing spring I23 is preferably selected of such force, adjusted if necessary by the nut I22, as to substantially counterbalance the weight of the back rest and also the average weight commonly imposed by the occupant upon the back rest. In some instances, as in the case of an unusually heavy patient, the operator may find it necessar to exert a small additional force to support the back. In other instances, as in the case of an occupant of light weight, it may be necessary for the operator to exert a small force in order to lower the back, but it has been found that by suitably selecting and adjusting the counterbalancing spring, the force required to be exerted by the operator may be reduced to a small amount capable of being exerted by one hand while grasping and operating the control handle "I9 for the locking mechanism. This relieves, in a large measure, the labor required of th operator in the adjustment of the back rest of the chair.

The combination with such a counterbalancing mechanism, of mechanism for lockingthe back against movement in either direction by a locking handle located as describedand automatically actuated to locking position, is highly convenient and advantageous in facilitating the ready adjustment and convenience of the chair. The provision of such two-way locking mechanism makes feasible the use of a substantial counterbalancing force approximately equaling the weight of the backrest and of the pressure thereon of the occupant of the chair, greatly reducing the effort required on the part of the operator, because it.

provides means for readily controlling the use of a counterbalancing force which may be greater in some cases than the combined weight of the backrest and of the pressure thereonof the occupant of the chair, and furthermore provides against any inadvertent upward movement of. the back by such counterbalancing means when the patient raises himself to an upright position. The back rest is positively locked against upward movement under any such conditions, the spindle 74 being self-locking inposition and prevented from sliding in the part 54 by reason of its threaded bearing in the part .54. Any downward pressure of the occupant, in excess of the counterbalancing force, tends to turn lever 61 clockwise in Fig. 11 and tighten the grip of the clamp on bar 39. These advantages are particularly important for some of the operators of such chairs,

as, for example, dentists, for the reason that one hand is oftenpreoccupied, leaving only one hand available to manipulate the lock and raise, or lower the back of the-chair.

In Figs. 14-48, inclusive,I have shown a modification of my invention wherein th arms 33 are loosely mounted on trunnions I3I, which are held in position in the lugs or supports 33 of the seat frame by means of setscrews I32. interposed between the meeting faces of the arms 36 and the supports 33 are cranks I33. The cranks. I33 ar held in position and rotated with the arms 36 by means of pins I35. Pivoted to the ends of the cranks I33 by means of pins I36 are rods I31. The rods I31 are enclosed by cored out portions of the seat frame 26 and are provided. with springs I38, which serve the same function as the spring I23. The upper ends of the springs seat on washers I39 which engage projecting parts I4I formed in th cored portions of the seat frame. The lower ends of the springs are seated upon nuts I42 threaded on the ends of the rods I31. The construction of the locking lever and the locking clamp in this modification is preferably the same as in the preferred form of invention, and it will be appreciated that the operation of the invention is substantially the same. The only essential differences lie in the provision of a spring in each side of the chair and the provision of a construction whereby the levers for connecting the back rest or support to the spring, as in the first modification, are eliminated, so that the parts for providinga counter-balancing action on the back rest are hidden from view by the seat frame.

It will thus be seen that the invention accomplishes the desired objects. It provides a counterbalancing means for the chair back of substantial force and effectiveness, in a simple and reliable form of construction, which is located in an accessible but out-of-the-way position on the chair, without interference with the other mechanisms of the back, and substantially out of View. The movement of the back, under the force of this counterbalancing means is easily and conveniently controlled by an efficient looking mechanism which operates automatically and positively, upon release, to clamp and lock the back against movement in either direction either by the weight of the occupant of the chair or the force of the counterbalance. This locking mechanism is so located and operated that the dentist or other operator of the chair, with a single hand and but a slight exertion, may both control the locking mechanism and raise or lower the chair back.

While I have shown the preferred form of my invention, it will be apparent that various modifications may be made in the form and relation of parts without departing from the spirit of my invention as set forth in'the appended claims.

I claim:

l. A chair of the character described comprising a seat, a back rest connected with said seat and movable to and 'from an inclined position, an element connecting said seat and back rest and movable relatively to said back rest during said inclining movement thereof, clamping means for engaging said element, a lever pivoted to said clamping means and extending in opposite directions from its pivotal connection therewith, one end of said lever being engaged by said back rest,means on said lever for actuating said clamping means, and positive actuating means on said back rest and engaging the other end of said lever for moving the same to actuate said clamping means to grip said element for securing said back rest in adjusted position.

2. A chair of the character described comprising a seat, a back rest connected with said seat and movable to and from an inclined position, an element connecting said seat and back rest and movable relatively to said back rest during said inclining movement thereof, clamping means for engaging said element, a lever pivoted to said clamping means and extending in opposite directions from its pivotal connection therewith, one end of said lever being connected with said back rest, means on said lever for actuating said clamping means, a member rotarily supported on said back rest and provided with means for positively actuating the opposite end of said lever to actuate said clamping means, spring means for rotating said memher to automatically clamp said element, and manual means for rotating said member to release said element for movement of said back rest.

3. An adjustable chair comprising a seat, a back rest connected with said seat and movable to and from an inclined position, a bar pivotally connected to said seat and movably connected with said back rest, clamping means for gripping said bar to hold said back rest against movement in either direction, a member rotarily supported on said back rest and connected with means for operating said clamping means, a manually operable element for rotating said member in one direction to actuate said clamp operating means and release said bar, and a spring having one end connected to said back rest and its other end to said member and tensioned to rotate said member in the other direction to actuate said clamp-operating means for clamping said bar.

4. An adjustable chair comprising a seat, a back rest connected with said seat and movable to and from an inclined position, an element pivotally connected to said seat and having a sliding engagement with said'back rest, clamping mechanism connected with said back rest or clamping said element to hold said back rest against movement, a member threadedly engaged with said back rest and connected with means for actuating said clamping mechanism to grip and release said element, a spring connected with said back rest and with said member for rotating the same in one direction to actuate said clamp actuating mechanism to grip said element, and a handle on said member for rotating the same in the opposite direction to actuate said clamp actuating mechanism to release said element.

5. An adjustable chair comprising a seat, a back rest pivotally connected with said seat and movable to and from an inclined position, an element pivotally connected with said seat and having a sliding engagement with said back rest during said inclining movement thereof, clamping means connected with said back rest for gripping said element to hold said back rest against movement, said clamping means having a lever pivoted thereto for actuating the same, a rotary member threadedly engaged with said back rest and engages with said lever, torsional spring means connected with said back rest and member for rotating the same in one direction to actuate said lever and clamping means to grip said element, and a handle on said member for rotating the same in the opposite direction to actuate said lever and clamping means to release said element for efiecting said inclining movement of said back rest.

ADAM J. MAY. 

